It is well known that knowledge is________treasure house，but practice is________key to it

In 1778, banks was elected ______ presidentof the Royal Society, ______ position he held for 42 years.

My father was mending his car while my mother .

My cousin had a bad cold last week.She coughed day and night.Which of the following is correct for the underlined part

When asked why he went there, he said he was sent there _____ for a space flight. [ ]